Liquid crystal display (LCD) devices are devices to control the transmission/shielding of light (on/off of display) by controlling the alignment of liquid crystal molecules having a birefringent property. Examples of LCD liquid crystal alignment modes include: a Twisted Nematic (TN) mode in which liquid crystal molecules with positive dielectric anisotropy are aligned in a twisted state in 90 degrees when viewing from a substrate normal direction; a vertical alignment (VA) mode in which liquid crystal molecules with negative dielectric anisotropy are aligned vertically to a substrate surface; and an in-plane switching (IPS) mode and a fringe field switching (FFS) mode, in which liquid crystal molecules with positive dielectric anisotropy are aligned horizontally to a substrate surface and a horizontal electric field is applied to a liquid crystal layer.
By forming an alignment film on a substrate, the liquid crystal display device can specify an initial orientation direction of the liquid crystal molecules by an interaction between side chains included in the alignment film and liquid crystal molecules. Further, in recent years, a technology in which the polymer layer (PSA layer) is formed by polymerizing monomers included in the liquid crystal composition to control the alignment of liquid crystal molecules has been drawing attention. In particular, a liquid crystal composition in which polymerizable components (hereinafter referred to as monomers for PSA) such as monomers, oligomers, or the like are mixed with the liquid crystal material is sealed between the substrates, and the PSA layer is formed by polymerizing the monomers for PSA by heating or light irradiation (e.g., with ultraviolet rays).
A method for further adding a polymerization initiator in the liquid crystal composition in addition to the monomers for PSA (e.g., see Patent Document 1), a method for adding polymerization initiator monomers (hereinafter referred to as polymerization initiator monomers) including a structure with a polymerization initiation function and including a radical polymerizable group, or the like have been considered as possible PSA techniques. Further, a method for forming an alignment film having a polymerization initiator functional group that has a function to start a polymerization reaction of the monomers for PSA on the substrate of the liquid crystal display device without adding the polymerization initiator or the polymerization initiator monomers to the liquid crystal composition (e.g., see Patent Document 2) has also been considered.